Diana, Princess of Wales, and Dodi Fayed were unlawfully killed by the reckless driving of their chauffeur, Henri Paul, and the paparazzi who chased them, jurors in the inquest into their deaths decided today.

The verdict, by a nine-to-two majority, brings to a close a six-month inquest that has heard from more than 240 witnesses and is expected to have cost more than £10m.

The verdict implicates the paparazzi and Paul much more so than previous investigations.

Dodi's father Mohamed Al Fayed, who has been insistent that Diana and his son were murdered and used the inquest to air his many conspiracy theories, said he was "disappointed" by the outcome.

The Harrods owner looked anxious and impassive as the verdict was delivered but then left for consultation with his entourage with what one journalist described as "a face of thunder".

When he emerged from the consultation room flanked by bodyguards he said: "The most important thing is it is murder."

The jury, who deliberated for more than three and a half days, had to deliver the same verdict on both Diana and Dodi. They were told they had to be "satisfied beyond all reasonable doubt" that the deaths were caused by gross negligence.

Diana's sons William and Harry thanked the jury for the "thorough way in which they have considered the evidence".

"We agree with their verdicts, and are both hugely grateful to each and every one of them for the forbearance they have shown in accepting such significant disruption to their lives over the past six months."

William and Harry also thanked the coroner, Lord Justice Scott Baker, and and said that they were particularly grateful to former bodyguard Trevor Rees "and to others who came forward to give evidence - in many cases reawakening their painful and personal memories."

"Finally, the two of us would like to express our most profound gratitude to all those who fought so desperately to save our mother's life on that tragic night."

The coroner set a very high threshold for returning an unlawful killing verdict on the deaths, saying it would be equivalent to a finding of manslaughter. It is one of the most serious verdicts they could have delivered.

Although a verdict of unlawful killing could trigger a criminal prosecution, British courts to not have the jurisdiction to try events in France and the coroner was not able to compel French paparazzi photographers to appear before the inquest. An earlier French investigation of the crash cleared the paparazzi photographers of responsibilty for the deaths.

Fayed thanked the jury for their time.

He insisted that the hearings were not a waste of time or taxpayers' money and said the inquest "established many new relevant facts withheld from the public."

"I am disappointed," he said in a statement. "It comes a blow to many people around the world who have supported my struggle."

He added that the French investigation and outcome of the Metropolitan police inquiry were wrong and that the inquest had proven that.

"The jury found new unidentified vehicles following the Mercedes," he said. "Who they are and what they were doing in Paris that night we will never know."

Meanwhile, Lord Stevens, the former Metropolitan police commissioner who produced a report in 2006 after a three-year investigation said he hoped everybody took the verdict as "closure to this particular tragedy" and that Diana and Dodi could now rest in peace.

"There has been an unprecedented amount of evidence given and gathered," Stevens said. "There have also been a number of allegations which have been unfortunate, particularly to the people who had a job to do and those who gave evidence."

He reminded reporters that Fayed stated during the inquest that he would accept whatever verdict the jury, which he fought to have, delivered.

Along with verdicts, the jurors had to decide on narrative factors they believed contributed to the deaths. They unanimously agreed that the fact the couple were not wearing seatbelts was a determining factor, as well as the way in which the Mercedes crashed into a pillar in the Alma tunnel. Experts have said there would have been less of an impact if the car had crashed into the wall instead of a pillar.

The coroner thanked the jurors for giving up six months of their lives for the hearings, and for the care they took in listening to the evidence.

Baker said it was almost "astonishing" that they got through the inquest with almost no absence or illness, and said their verdict was a "defining moment in history".

The 11 jurors, who appeared to be hugely relieved after keeping long hours during 91 days of evidence, have been dismissed from jury service for life.

The verdict is also significantly different from those reached by a two-year French investigation, which placed the blame solely on gross negligence by Paul.

But the photographers refused to give evidence to the hearing and the coroner was unable to force them to do so, making it difficult for the jury to get a clear picture of what had happened.

Fayed said it was "shocking" that the French police, paparazzi, pathologists, Queen and Prince Philip were not forced to give evidence and that they "should not be above the law."

"MI6 really know what happened," he said.

The involvement of Paul was less surprising given the conclusions of the two previous inquiries.

Bar receipts from the city's Ritz hotel, where Paul was the head of security, showed he had drunk two Ricards - equivalent to four single shots of whisky - before driving the princess and Fayed.

While CCTV footage of Paul - who also died in the crash - just before he left the hotel showed him to be relatively sober, blood tests and other samples revealed he was three times over the French drink-drive limit.

They also revealed traces of prescribed drugs - Prozac, for the treatment of depression, and Tiapridal, which counters alcohol dependency.

Fayed has maintained the samples were faked or switched, pointing to question marks over the labelling of vials of blood. The Harrods owner has claimed the samples were lost or destroyed, and that questions remained over a DNA test on sample that appeared to show it was from Paul.

During the inquest, jurors heard from Myriah Daniels, Fayed's personal massage therapist, who said Paul's driving had been reckless when he came to collect her from the airport on the day of the crash.

Darmon also told the inquest that Paul had "the behaviour of an alcoholic". He said: "My father was an alcoholic. Mr Paul … reminded me of my father - his eyes, the way he acted, that's what I thought."

The verdict was one of five possible judgments that the coroner had told the jurors they could deliver.

The others were unlawful killing by grossly negligent driving of paparazzi vehicles behind the car carrying the princess, unlawful killing by carelessness of Paul, an accidental death verdict if none of the previous verdicts were established, or an open verdict.

The purpose of a British inquest is to determine who died, when, where and how. The six-month hearing into Diana and Dodi's deaths was clouded by a flurry of conspiracy theories, colourful witnesses and evidence tarred by lies.Today's decision firmly lays to rest the many conspiracy theories put forward by Dodi's father.

He has long insisted that the couple were murdered by the MI6 at the behest of the royal family so the "Nazi" Duke of Edinburgh would not have to endure the "shame" of the princess marrying a Muslim.

He further claimed that Diana was pregnant with his son's child.

The inquest served as a platform for him to vent many of these theories, and he accused virtually everyone involved in the Diana investigation of being part of a plot to kill her and his son.

However, during his summing up, the coroner said there was no evidence of involvement by Prince Philip or MI6 in the deaths.

He said there was plenty of evidence that some witnesses, including many of Fayed's most senior staff, had lied.

The jurors, who were sworn in on October 2 last year, consisted of six women and five men.

As the hearings began, the coroner told them: "You will be in the public eye as no inquest jury has ever been before."